The longer I study Spanish (lazily over the past few years), the more I defer to books. I am not even half way through this book, but I can already tell it’s a better idea than learning from a native speaker (update even further into the book: this thought is consistent). Just like learning to dance salsa from a gringo (ie someone who had to learn themselves) is better than from a Colombian who danced all their lives, learning Spanish from someone who had to really struggle through and master it enough to write a book is the better option.
That’s not to say there isn’t a place for teachers, but beware that they often teach the correct way of speaking rather than the common way. Use a teacher to get started in a language if you’re unsure where/how to start, use them to correct your pronunciation, use them to explain deeper topics you can’t figure out for yourself. But don’t rely on them to make you fluent. It simply won’t happen.
Once I read this book and synthesize the information into my notes I will add it to my Spanish Language Cheat Sheet.